The X-ray Structures of [Fe(CO)3(η4-6-exo-(PPh2R)cyclohepta-2,4-dien-1-one][BF4] (R = Me or tBu)

The structures of [Fe(CO)(3)(eta(4)-6-exo-(methyldiphenylphosphine)cyclohepta-2,4-dien-1-one][BF4] [orthorhombic, a = 12.3269(4), b<bold> = </bold>13.5243(5), c = 13.7127(4), space group Pna2(1)] and [Fe(CO)(3)(eta(4)-6-exo-(tert-butyldiphenylphosphine)cyclohepta-2,4-dien-1-one][BF4] [monoclinic, a = 9.7947(3), b<bold> = </bold>12.8766(3), c = 20.2168(5), beta = 91.089(3), space group P2(1)/c] have been determined. The disordered tetrafluoroborate ion in [Fe(CO)(3)(eta(4)-6-exo-(methyldiphenylphosphine)cyclohepta-2,4-dien-1-one][BF4] sits between two of the cations and displays interactions with hydrogen atoms in the ortho- position of the phenyl rings, the methyl group and the 6-position of the seven-membered ring. There is also close contact between the ketone oxygen atom and two protons in another cation, a proton of the methyl group and the proton in the 5-position of the seven-membered ring. The tetrafluoroborate anion in [Fe(CO)(3)(eta(4)-6-exo-(tert-butyldiphenylphosphine)cyclohepta-2,4-dien-1-one][BF4] is not disordered and shows close contacts with protons in three cation units. In one cation the interaction is with two protons from separate methyl groups of the tert-butyl substituent. The remaining interactions are with a proton in the ortho- position of a phenyl ring in one cation and the proton in the 2-position of the seven-membered ring. There is also an interaction between the ketone oxygen and a proton from the tert-butyl group in another cationic unit.